Control system and equipment configuration for a modular product assembly platform

ABSTRACT

A modular product assembly platform which includes a multiple number of industrial robots or other similar assembly devices. The product assembly platform also includes a programmable controller system housed in a logic control cabinet, a vision control system housed in a vision control cabinet and a set of robot controllers which operate together to control the robots or assembly devices for performing product assembly tasks. The layout and configuration of the platform and the control equipment provide for convenience and flexibility in configuring and reconfiguring the assembly platform for different assembly procedures associated with different products.

BACKGROUND OF THE INVENTION

The present invention relates to industrial automation equipment andmore particularly relates to modular platform units for performingproduct assembly procedures.

In the past, product assembly processes have usually been performed bycustom designed assembly machinery which have been dedicated toparticular assembly tasks. In accordance with this conventional approachthe design and construction of automated assembly lines requiredenormous engineering expenditures and involved high risks to provefunctional equipment compliance. Furthermore, once such assembly lineswere constructed, they were completed specialized to the limitedapplications for which they were built and were not reusable for theassembly of different products. The assembly units making up theassembly line could be recovered in the event manufacturing operationswere discontinued, however, in most cases, extensive redesign andreconstruction was necessary to adapt the equipment for use inassembling new products.

It is therefore an object of the present invention to provide a controlsystem and configuration for a modular product assembly platform thatallows for the platform to have flexibility and reusabilitycharacteristics so that the platform can be adapted for assemblingalternate or different products with a minimum of cost and effort.

It is a further object of the present invention to provide a controlsystem and configuration for a modular product assembly platform whichallows for the efficient and effective use of assembly robots andmachine vision equipment.

It is yet another object of the present invention to provide a controlsystem and configuration for a modular product assembly platform whereinthe system is generically programmable and is interfaced with adaptablerobotic configurations.

It is a yet further object of the present invention to provide a controlsystem and configuration for a modular product assembly platform whichfacilitates factory automation projects, allows platforms to be broughttogether to perform different types of assembly procedures and optimizesproduction efficiency in terms of equipment utilization, control andcycle time requirements.

SUMMARY OF THE INVENTION

The present invention constitutes a control system and equipmentconfiguration for a modular product assembly platform which includes amultiple number of industrial robots or specialized product assemblymachines. The robots are detachably mounted on a specially designedplatform deck and include moveable robot arms on which video cameras maybe mounted as part of a machine vision system and tooling adapted forperforming product assembly tasks. Robot controllers for separatelydirecting the operation of the individual robots are mounted underneaththe deck. A general purpose programmable controller for controlling theassembly process across the entire platform is mounted in a cabinet atone end of platform. A user configurable machine vision system ismounted in a cabinet at the other opposite end of the platform for usein identifying and locating parts in coordination with the operation ofthe robots. The product assembly platform also includes a conveyancesystem for transporting parts and products under assembly across thedeck past the robots. The robot controllers are configured forcontrolling the "geographic" positioning of the moveable arms of therobots. The vision system provides information for recognition of partsand the proper alignment and positioning of parts and robot arms. Theprogrammable controller system provides overall control and coordinationfor the robots, vision system, robot controllers, assembly tooling onthe robot arms and the conveyance system.

In operation, either stationary or robot arm mounted video cameras arepositioned so that the parts to be worked on will be located in theirfield of view. Either the programmable controller or one of the robotcontrollers commands the vision system to capture images (take apicture) of the parts. The stored image attributes are analyzed by thevision system per preprogrammed instructions. For "recognition" typeapplications such as presence sensing and gauging, the information isprovided to the programmable controller for subsequent operation. Forrobot "guidance" type applications, the coordinate location and rotaryposition of the part is determined by the vision system in conjunctionwith the robot controller's calibration function. The information isused by the robot controller to position the robot arm mounted toolingto perform the required task. When the tool is in position, theprogrammable controller signals the tooling to execute the productassembly task associated with each assembly process step. Theprogrammable controller signals the robot controllers and the visionequipment to proceed from one assembly process step to another incoordination with the operation of the conveyance system as partsproceed across the platform in accordance with the desired assemblyprocedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an elevated perspective view of a modular productassembly platform in accordance with the present invention.

FIG. 2A provides an elevated perspective view of the frame, raised deck,robots and conveyance system of a modular product assembly platform inaccordance with the present invention.

FIG. 2B provides an elevated perspective view of control cabinets andwiring cabinets of a modular product assembly platform in accordancewith the present invention.

FIG. 3 provides a plan view of the inside of a typical power controlcabinet for a product assembly platform in accordance with the presentinvention.

FIG. 4 provides a plan view of the inside of a typical logic controlcabinet for a product assembly platform in accordance with the presentinvention.

FIG. 5 provides a plan view of the inside of a typical vision controlcabinet for a product assembly platform in accordance with the presentinvention.

FIG. 6 provides a plan view of the inside of a typical wiring cabinetfor housing power, communication and control lines in a product assemblyplatform in accordance with the present invention.

FIG. 7 provides a cross-sectional view of the mounting system forsecuring the pedestal of a robot or other assembly device onto theraised deck of a modular product assembly platform in accordance withthe present invention.

FIG. 8 provides an overall diagrammatic block diagram view of thecontrol system and flow of control information for a product assemblyplatform in accordance with the present invention.

FIG. 9 provides a diagrammatic block diagram view with respect to asingle robot depicting typical control information signal pathsincluding vision recognition and/or robot guidance signal paths inaccordance with the present invention.

FIGS. 10A, 10B and 10C provide flowcharts depicting the steps in typicalproduct assembly steps corresponding to the block diagram view of FIG. 9in accordance with the present invention.

FIGS. 11 provides a block diagram illustrating the use of various sizeassembly platforms to implement a multi-step assembly process for afactory assembly line.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1, 2A and 2B, a modular product assembly platform10 is shown as including a frame 12 having a raised deck 14 on which aset of three industrial product assembly robots 16 are removablymounted. The platform 10 also includes a conveyor 20 for transportingparts 25 on trays 17 from the near end 11 of the deck 14 to the far end13 of the deck 14 past the robots 16. The robots 16 compriseconventional industrial robots (one of which is a cartesian robot andtwo of which are SCARA robots) having movable arms 22 and specializedtools 18 such as grippers, screwdrivers, welding appliances and the likeattached to the outer ends of the movable arms 22 for performing productassembly tasks. Support stands 21 are adapted for storing alternativerobot tools or tooling 18 which may be interchangeably used by therobots 16. Video cameras 24 are mounted either on the arms 22 of therobots 16 or on stationary supports for recognition and locationdetection of the parts 25 on the trays 17 being worked on by the robots16.

The arms 22 of the robots 16 are individually controlled by three robotcontrollers 26 installed in bays 28 underneath the deck 14 and by aprogrammable controller system 90 (see FIG. 4) mounted within a logiccontrol cabinet 30 at the far end 13 of the platform 10. The robotcontrollers 26 control positioning of the movable arms 22 on the robots16 while the programmable controller 90 regulates the assembly processsteps to be performed and, in particular, controls the operation of thetooling 18 in coordination with the selection of the movement steps tobe performed by the robot arms 22. The video cameras 24 are controlledby a vision control system 110 (see FIG. 5) mounted within a visioncontrol cabinet 34 on the near end 11 of the platform 10 which in turnoperates under direction of the programmable controller system 90 at thefar end 13 of the platform 10 in the cabinet 30. The control console 40provides an operator interface for allowing operator control over themachinery on the platform 10 while the power control cabinet 42 housesvarious electrical power distribution and control elements subject toregulation by the operator through the use of the control console 40.The control console 40 includes a set of power control pushbuttons 41for manually turning platform machinery on and off, an input panel 43for manual sequencing of platform machinery through their controlprograms and a numerical keypad and corresponding LCD display 45 forentry of control parameters and the like. A wiring and communicationsconduit 50 comprised of wiring and control cabinets extends around theperiphery of the raised deck 14 for housing power distribution, controland communication lines as well as small size relays and terminal stripsmounted on DIN rails. The conduit 50 includes the cabinets 42, 64, 30,62, 34 and 66 which form a continuous ring encircling the entireplatform deck 14. A data display unit 52 is mounted above the console 40for displaying operating information and especially platform operatingfault notices in response to signals from the programmable controllersystem 90. The superstructure 46 may be used to house pneumatic linesfor providing pneumatic power along the edge of the deck 14 fromalongside the conduit 50.

In operation, the platform 10 provides for parts 25 to be transportedpast the robots 16 on the conveyor 20. The robots 16 may perform variousassembly tasks on the parts 25 as they pass by on the conveyor 20 inaccordance with programs executed by the programmable controller system90 in the cabinet 30 as selected by the operator through the use of thecontrol console 40. The vision control system 110 within the cabinet 34provides parts recognition and robot arm guidance information to therobot controllers 26 and the programmable controller system 90 in thecabinet 30. The configuration of the platform 10 allows for a great dealof flexibility in programming and reprogramming the overall systemrepresented by the platform 10 for accomplishing different sets ofassembly tasks on different types of products.

Referring now to FIG. 3, the power control cabinet 42 comprises a sheetmetal enclosure which can be accessed through two outward opening doors.The cabinet 42 houses a main disconnect switch 79, a motor drive unit 80for the conveyor 20, two control circuit transformers 82, a DC powersupply 83, a set of terminal strips 84 for making electrical control andpower distribution connections, a set of control relays 85 and a set ofoverload relays 87. The transformers 82 provide AC power to theelectrical machinery mounted on the platform 10 such as the robots 16.The motor drive 80 controls the operation of the conveyor 20. Theterminal strips 84 enable the motor drive 80, transformers 82, relays 85and 87 and power supply 83 to be conveniently interconnected with theconsole 40 and the electrical machinery of the platform 10. The cabinet42 is connected to the cabinets 64 and 62 at openings 63 and 65 forenabling the passage of power, control and communications lines.

Referring now to FIG. 4, the logic control cabinet 30 comprises a sheetmetal enclosure which can be accessed through two outward opening doors.The cabinet 30 houses a conventional programmable controller system 90having a chassis 92 in which power supply, logic processor, and I/Omodules are mounted. In the present case the programmable controllersystem 90 comprises a power supply 89, a logic processor module 91 andsixteen I/O modules 93. The system 90 allows control instructions in theform of an industrial control program such as ladder logic programsresident in the memory of the logic processor module 91 to be executedto examine the state of selected inputs at modules 93 and thereaftercontrol the state of selected outputs at modules 93 depending upon thestate of one or more of the inputs. Large numbers of inputs may beexamined by the system 90 at the same time as it controls large numbersof outputs. The wiring by which the system 90 is connected to sensingand control output devices (such as tooling 18) is generally directedthrough the casing 95 within which multiple terminal strips are mountedfor establishing the required electrical interconnections. Thecommunication cables 97a, 97b and 97c connect communication ports on theprocessor module 91 to the remote I/O rack 100 (FIG. 5), the visionsystem 110 (FIG. 5), control console 40 and data display unit 52 viaconventional packet network communication links. The power, control andcommunication lines for the system 90 pass through conduits 62 and 66 tothe sensing devices, electrical machinery and the control equipment ofthe platform 10 which work under the control of the programmablecontroller system 90.

Referring now to FIG. 5, the vision control cabinet 34 comprises a sheetmetal enclosure which can be accessed through two outward opening doors.The cabinet 34 houses a remote I/O rack 100 containing a power supplymodule 102, six remote I/O modules 104 and a communications adaptermodule 106. The communications adapter module 106 links the remote I/Orack 100 to the programmable controller system 90 by way of the cable97b connected to a communications port on processor module 91 in thechassis 92. The remote I/O rack 100 allows for input and output servicesrelated to the control program of the system 90 to be resident at thenear end 11 of the platform 10 within the cabinet 34. The cabinet 34also contains a user-configurable vision control system 110 which isadapted for receiving video input from the video cameras 24. The visioncontrol system 110 includes a power supply 112 and a vision controlmodule 114 having the capability of working with multiple video cameras(although multiple vision control modules 114 could be used). The visioncontrol module 114 is separately connected by the video signal cables117 to each of the video cameras 24 on the robots 16. The vision module114 is also connected to the robot controllers 26 and is connected tothe programmable controller system 90 via the communications cable 97awhich is connected to one of its communications ports for establishing acommunications network link with the controller system 90. The visionsystem 110 may also communicate with the controller system 90 by way ofthe I/O rack 100. The wiring by which the systems 100 and 110 areconnected to the sensing and control output devices is generallydirected through the casing 105 within which multiple terminal stripsare mounted for establishing the required electrical interconnections.The power, control and communications lines for the systems 100 and 110pass through the cabinets 64 and 66 of the conduit 50.

Referring now to FIG. 6, the cabinet 66 of the conduit 50 is typical ofthe cabinets 62, 64 and 66 and comprises a sheet metal enclosure whichcan be accessed by unscrewing and removing its outer cover. The cabinet66 houses multiple sets of wires 130 for distributing power to theelectrical machinery on the platform and for conducting control andcommunications signals between the electrical machinery on the deck 14and the programmable controller system 90, the I/O rack 100, the robotcontrollers 26 and the vision system 110. Terminal strips 132 andcontrol relays 133 are mounted on a DIN rail 134 within the cabinet 66.The terminal strips 132 allow for easy interconnection of the wiringwithin the cabinet 66 while the relays 133 provide for control in theimmediate vicinity of platform machinery. The cabinets 62, 64 and 66 arecharacterized by access ports opening onto the deck 14 for passage ofwiring to the electrical machinery and control equipment on and underthe deck 14. The conduit 50 provides a highly useful function inallowing complete electrical interconnection all around the periphery ofthe deck 14 of the platform 10 thereby facilitating the efficientinterconnection of the machinery and control equipment of the platform10 and enabling convenient configuration and reconfiguration of theplatform 10 for different product assembly applications.

Referring now to FIG. 7, the pedestals 140 for mounting the robots 16are mounted onto the deck 14 using rails 142. The rails 142 runlengthwise across the deck 14 parallel with the conveyor 20. Each of therails 142 has a special cross-section in the form of a modified T shapeincluding a downward facing incline 144 on one lateral side and whichintersects the deck 14 at an acute angle an overhanging ledge 146 on itsother lateral side which intersects the deck 14 at a right angle. Eachpedestal 140 mounts onto two rails 142 using two recessed tracks 150 and152 running parallel across its base plate 154 and two mounting blocks156 and 158 which can be drawn upward toward the plate 154 by bolts 160and 162. The mounting block 156 has the shape of an inverted T formating with a ledge 146 while the mounting block 158 has an incline 155along one of its faces for mating with an incline 144. To providevertical stability and alignment, the bolt 160 draws up the block 156against the bottom 164 of the ledge 146 and the track 150 so that therail, and more particularly, the ledge 146 is trapped between the block156 and the plate 154. To provide horizontal alignment and stability,the bolt 162 draws up the block 158 against the incline 144 in order topush the outer lateral edge 166 of the ledge 146 of the rail 142 againstthe outer wall 168 of the track 152. Together the rails 142, tracks 150and 152 and blocks 156 and 158 provide a very stable and accuratemounting and alignment system for the pedestals 140 and the robots 16.

Referring now to FIG. 8, the electrical control system of the platform10 includes the programmable logic controller system 90, the robotcontrollers 26 and the vision control system 110. The programmable logiccontroller system 90 is responsible for overall coordination and controlof the electrical machinery on the platform 10. The robot controllers 26direct the actual mechanics for "geographic" positioning of the robotarms 22 of the robots 16. The vision control system 110 receives videoinput from the cameras 24 associated with the robots 16 and in responseperforms various recognition and robot guidance functions with respectto which it may transmit data to the controller system 90 and/or robotcontrollers 26. When the robot arms 22 and parts 25 are in properalignment the programmable logic controller system 90 actuates thetooling 18 to perform the appropriate assembly tasks.

Referring now to FIGS. 9, 10A, 10B and 10C, the flow of control signalsassociated with a particular robot 16 in a typical control system asshown in FIG. 9 takes place in a series of sequential control steps asshown in FIGS. 10A, 10B and 10C. In step 200 the programmable controllersystem 90 signals the robot controller 26 that the next product assemblystep should be undertaken. In response the robot controller 26 transmitscontrol signals to the robot 16 for directing movements of the robot arm22 and the arm 22 is repositioned in accordance with step 202 so thatthe camera 24 (mounted on arm 22) is in position to take a picture of apart. As indicated in step 204 different vision/control routines arefollowed for guidance or recognition applications (other types ofvision/control routines could also be followed). If a robot guidanceapplication is involved both the controller system 90 and vision system110 "jointly" regulates operations in accordance with the guidanceroutine of FIG. 10B If a recognition application such as presencesensing or gauging is involved the controller system 90 regulatesoperations in accordance with the recognition routine of FIG. 10C.

Referring now to FIG. 10B, in a guidance application, the robotcontroller 26 signals the vision system 110 as per step 220 that thevideo camera 24 is in position to spot a part to be worked on inaccordance with its most recent positioning of the robot arm 22.Thereafter, the vision system 110 controls the camera 24 to take a"picture" of the location where the part is positioned in accordancewith step 221. After the picture is taken and the attributes of theimage are analyzed by the vision system 110 per preprogrammedinstructions in step 222, the vision system 110 transmits coordinates tothe robot controller 26 in step 223 indicating the location and rotationof the part with respect to its own vision coordinate frame ofreference. The robot controller 26 then transforms the visioncoordinates into its own robot coordinate frame of reference (per apreprogrammed initial calibration procedure) and repositions the robotarm 22 to the desired position for further operations as per step 224 inaccordance with the coordinate information from the vision system 110.Once the robot arm 22 has been moved into position the robot controller26 signals the controller system 90 in step 225 that the robot arm 22 isnow in position for the tooling operation to be performed.

Referring now to FIG. 10C, in a recognition application, the robotcontroller 26 signals the controller system 90 as per step 230 that thevideo camera 24 is in position to spot a part to be recognized inaccordance with its most recent positioning of the robot arm 22. Asindicated in step 231 the controller system 90 then signals the visionsystem 110 that the camera 24 is in position and, thereafter, the visionsystem 110 controls the camera 24 to take a picture of the locationwhere the part may be located in accordance with step 232. After thepicture is taken and the attributes of the image are analyzed by thevision system 110 per preprogrammed instructions in step 233, the visionsystem 110 transmitted either a "Go" or "No Go" signal to the controllersystem 90 based on its analysis of the presence or characteristics ofthe part.

Referring back to FIG. 10A, following the execution of the guidanceroutine of step 206, the controller system 90 transmits appropriatecontrol signals for actuating the tooling 18 to perform the assemblytask associated with the current assembly process step as indicated instep 212. After a short delay for the tooling to accomplish its task,the controller system 90 proceeds to the final step 214. On the otherhand, following the execution of the recognition routine of step 208,the controller system 90 responds to the "Go" or "No Go" signal from thevision system 110 in accordance with step 210 by either actuating thetooling 18 pursuant to step 212 in the case of a "Go" signal orproceeding to step 214 in the case of a No Go signal. In step 214, thecontroller system 90 queries whether the last step in the overallassembly procedure has now been executed and either halts operations ifthe last step has been executed or jumps back to step 200 if the laststep has not been executed.

Referring now to FIG. 11, multiple product assembly platforms 10a-fhaving different configurations of robots 16 may be used in combinationto perform complicated assembly procedures comprising multiple assemblysteps. In particular, the product assembly platforms 10a and 10e and 10ffeed parts to the main assembly line consisting of platforms 10b, 10cand 10d where the parts are incorporated into the final product atplatforms 10c and 10d, respectively. A network controller 250 is incommunication with the programmable controller systems on platforms10b-f and conveyance device 256 for coordinating platform operations andregulating the operation of the conveyance device 256 for controllingthe transfer of parts between platforms. The modular nature of theplatforms 10a-f allows them to be used as building blocks in assemblysystems for factories. The platforms 10a-f have a great advantage inthat they can be easily reprogrammed or reconfigured in new arrangementsfor the assembly of different products without rebuilding and retoolingof the entire factory floor on which the platforms are installed.

While particular embodiments of the present invention have been shownand described, it should be clear that changes and modifications may bemade to such embodiments without departing from the true scope andspirit of the invention. It is intended that the appended claims coverall such changes and modifications.

We claim:
 1. A modular product assembly platform, comprising:a pluralityof industrial robots adapted for assembly tasks including robot arms androbot tools; a deck for mounting said industrial robots having first andsecond sides and first and second ends including means for detachablymounting said robots; a plurality of robot controllers for controllingthe geographic positioning of said robot arms including said robottools; a conveyance system for transporting parts or products underassembly across said deck past said robots; a programmable controllermounted at said first end of said deck for coordinating the operationsof said robots by controlling the positioning of said robots armsthrough said robot controllers, by directly controlling said robot toolsand by directly controlling said conveyance system for product assembly;and a user configurable vision system mounted on said second end of saiddeck for use in identifying and locating products or parts incoordination with the operation of said industrial robots.
 2. Theproduct assembly platform of claim 1, wherein said means for detachablymounting includes a set of standardized mounting rails secured to aplanar mounting bed and said platform further includes one or morestandardized sets of utility service outlets along said first side ofsaid deck adjacent to said mounting bed.
 3. The product assemblyplatform of claim 1, further including a control console mounted alongsaid first side of said deck for communicating with said controller andenabling operator control over said platform and a message displaydevice mounted above said control console and connected to saidprogrammable controller.
 4. A product assembly network which may bereadily reconfigured to assemble different products, comprising:A) aplurality of modular product assembly platforms each of which includes:adeck for mounting industrial robots having mounting gear for mountingsaid robots onto said deck, a plurality of industrial robots adapted forperforming product assembly tasks which are detachably mounted on saiddeck and each of which includes a movable robot arm and a robot toolattached to this arm, a conveyance system for transporting productsunder assembly across said mounting deck past said robots, a pluralityof robot controllers one of which is associated with each of said robotsfor controlling the geographic positioning of the arm of the robot withwhich each robot controller is associated, a programmable controller forregulating and coordinating the operations of said robots by actuatingsaid robot controllers to control said robots in performing robot armpositioning operations and directly controlling the operation of saidrobot tools on said robots and said conveyance system for productassembly purposes; and B) means for conveying products and parts betweensaid modular platforms; and C) a network controller in communicationwith said programmable controllers on said platforms for regulating andcoordinating the operations of said platforms and said means forconveying products or parts.
 5. The product assembly network of claim 4,wherein said network controller comprises a programmable controllerwhich is integrated with an information processing system capable ofexecuting general purposes computer programs.
 6. The product assemblynetwork of claim 4, wherein said platforms further include userconfigurable vision systems for use in detecting the position ofproducts or parts in coordination with one or more of said robots onsaid platforms.
 7. The product assembly network of claim 4, wherein saidplatforms further include a control console mounted along one side ofeach of the platforms which is connected to and in communication withthe programmable controller for the platform.
 8. The product assemblynetwork of claim 7, wherein the mounting gear one each of said platformsincludes a set of standardized mounting rails and each platform furtherincludes one or more standardized sets of utility service outletsadjacent to said mounting deck.
 9. The product assembly network of claim7, wherein each of said platforms further include a message displaydevice mounted above said control console and connected to and incommunication with the programmable controller for the platform.
 10. Amodular product assembly platform, comprising:a plurality of industrialassembly machines; a deck for mounting said assembly machines; a set ofmounting gear for detachably securing said assembly machines onto saiddeck at variable locations including; a set of mounting railscharacterized by a modified T shape having an incline on one lateralside which intersects said deck at an acute angle and a notch its on theother lateral side which intersects said deck at a right angle; aplurality of machine control units mounted under said deck and connectedto said machines for controlling said machines; a conveyance system fortransporting products under assembly across said mounting bed past saidassembly machines from a first side of said bed to a second side of saidbed; a programmable controller connected to said machine control unitsfor controlling and coordinating the operations of said machines andsaid conveyance system for product assembly purposes; and a controlconsole mounted along a third side of said platform for communicatingwith said programmable controller.
 11. The product assembly platform ofclaim 10, further including a data display unit for displaying messagespertinent to operations taking place on the platform which is mountedabove said control console and connected to said programmablecontroller.